It is known that a polymer prepared from a polymerizable compound having a perfluoroalkyl or perfluoroalkenyl group and an acrylate or methacrylate group is useful as a water- and oil-repellent agent used for a textile and woven fabric. Particularly an aqueous dispersion wherein said polymer is dispersed in an aqueous medium with an emulsifier is industrially and widely used.
A water- and oil repellent agent processing bath prepared by diluting conventional aqueous dispersions, however, often has the problems that a impurity attached to a processed fabric during a pretreatment step incorporates into the bath in a treatment step, and then the dispersibility of the aqueous dispersion is deteriorated, emulsion particles may agglomerate and precipitation may be caused, or the dispersion is broken because of a mechanical impact exerted when a treated fabric enters into the bath or leaves from the bath, emulsion particles may agglomerate and precipitation may be caused, so that the water- and oil-repellency performance is deteriorated and the polymer attaches to a roll to give a soiled fabric. That is, the conventional aqueous dispersions are insufficient in stability against impurity and mechanical stability during treatment step.
Methods having excellent stability against impurity are proposed in JP-A-9-118877, JP-A-9-125051 and JP-A-9-302335, but do not always provide sufficiently satisfactory stability in connection with variety of recent water- and oil-repellent treatments.